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Old 15th June 2009, 02:10 PM   #1
Cassiel is offline Cassiel  Libya
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Default Does this power supply make any sense to you?

I like checking what the manufacturers are doing today, especially the Japanese. Well there is this EL84 PP amp and i start looking at the power supply and i donīt understand what this diode is doing there. See picture:

What kind of rectifier is this? Half wave?
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Old 15th June 2009, 02:13 PM   #2
Cassiel is offline Cassiel  Libya
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Original amp.
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Old 15th June 2009, 02:47 PM   #3
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Probably a voltage doubler

http://www.tubecad.com/january2000/page14.html
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Old 15th June 2009, 03:31 PM   #4
Cassiel is offline Cassiel  Libya
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Thanks!

I have used voltage doublers before but never seen a half wave one.
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Old 15th June 2009, 03:43 PM   #5
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This doesn't make sense to me. The diode across the secondary will short it when it is forward biased.
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Old 15th June 2009, 04:25 PM   #6
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Sawreyrw is correct. As drawn, it's a recipe for disaster. The diode across the secondary will short the transformer out and burn it up. For a voltage doubler, there must be a second capacitor in series with the first (shunting) diode. If you drew this from the existing amp, please recheck it again.
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Old 15th June 2009, 04:25 PM   #7
Cassiel is offline Cassiel  Libya
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It is difficult to reverse engineer this power supply, it makes no sense!

It has to be a half wave voltage doubler, see a better pic.


http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=152516
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Old 15th June 2009, 04:38 PM   #8
Cassiel is offline Cassiel  Libya
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You can see that those diodes go to the same point and one ends in ground. Maybe is a half wave with 2 diodes in series but one is grounded so it cannot be,maybe it is just my mistake following those wires, and all this just out of curiosity....i know the amp sounds great.
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Old 15th June 2009, 07:28 PM   #9
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Quote:
Originally posted by stalker
You can see that those diodes go to the same point and one ends in ground. Maybe is a half wave with 2 diodes in series but one is grounded so it cannot be,maybe it is just my mistake following those wires, and all this just out of curiosity....i know the amp sounds great.

It all makes sense if one assumes that the black wires cross under the terminal strip as shown here in blue. That makes it a regular voltage doubler.

I think of a voltage doubler as neither half wave or full wave. It's more like two half wave rectifiers on opposite AC half-cycles, in series.

Cheers,

Michael
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Old 15th June 2009, 07:31 PM   #10
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It would be according to this schematic:
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